RESUMO
Interactions between Zoophthora radicans isolates were studied in vitro and in vivo during infection of Plutella xylostella larvae. We distinguished between isolates within infected hosts using PCR-RFLP. Isolates obtained from P. xylostella larvae (NW386 and NW250) were more virulent than isolates from other insect hosts. Isolate NW250 was most virulent at 27°C and isolate NW386 was most virulent at 22°C. In vitro growth of all isolates except NW386 was affected by the presence of other isolates. During in vivo interactions between NW250 and NW386, the isolate with the greatest conidial concentration at inoculation infected more larvae than its competitor. Dual infected larvae were only found in treatments where inoculation concentrations of conidia were high for both isolates. Where concentrations of conidia at inoculation were low for both isolates, only NW250 caused successful infection. The implications of these results for the ecology of Z. radicans are discussed.
Assuntos
Entomophthorales/fisiologia , Interações Hospedeiro-Patógeno , Mariposas/microbiologia , Controle Biológico de Vetores , Animais , Entomophthorales/patogenicidade , Larva/microbiologia , Esporos Fúngicos/fisiologia , Temperatura , VirulênciaRESUMO
Vector control is a key means of combating mosquito-borne diseases and the only tool available for tackling the transmission of dengue, a disease for which no vaccine, prophylaxis, or therapeutant currently exists. The most effective mosquito control methods include a variety of insecticidal tools that target adults or juveniles. Their successful implementation depends on impacting the largest proportion of the vector population possible. We demonstrate a control strategy that dramatically improves the efficiency with which high coverage of aquatic mosquito habitats can be achieved. The method exploits adult mosquitoes as vehicles of insecticide transfer by harnessing their fundamental behaviors to disseminate a juvenile hormone analogue (JHA) between resting and oviposition sites. A series of field trials undertaken in an Amazon city (Iquitos, Peru) showed that the placement of JHA dissemination stations in just 3-5% of the available resting area resulted in almost complete coverage of sentinel aquatic habitats. More than control mortality occurred in 95-100% of the larval cohorts of Aedes aegypti developing at those sites. Overall reductions in adult emergence of 42-98% were achieved during the trials. A deterministic simulation model predicts amplifications in coverage consistent with our observations and highlights the importance of the residual activity of the insecticide for this technique.